Agitating feeder and compression molding machine

ABSTRACT

An agitating feeder is provided in a compression molding machine that includes at least one die having a die bore, an upper punch and a lower punch retained respectively above and below the die so as to be vertically slidable, and a compression mechanism for compressing and molding a powdery material filled in the die bore by the upper punch and the lower punch. The agitating feeder includes an agitating rotor for rotating to agitate the powdery material, a housing accommodating the agitating rotor, and a gas flow device for flowing gas in the housing.

BACKGROUND OF THE INVENTION

There has been known a compression molding machine including anagitating feeder that agitates a powdery material and feeds the agitatedpowdery material in a die, in order to uniformly fill the powderymaterial in the die. The agitating feeder includes a housing andagitating rotors that are accommodated in the housing and rotate indirections opposite to each other. While agitating a powdery material inthe housing, the agitating feeder fills the powdery material in each diethat passes below the agitating rotors, so that the powdery material isfilled in the respective dies uniformly in terms of quantity. Theagitating rotors are mounted in the housing so as to rotate above aturret with no contact made therebetween (refer to Japanese RegisteredUtility Model Publication No. 3052283, for example).

However, in a case where a particularly fine powdery material is filledin a die bore, the powdery material aggregates in some cases and may notflow smoothly. As a result, the powdery material may not be uniformlyfilled in a die bore. Further, the powdery material may be accumulatedin a region downstream in the rotation direction of the turretaccommodated in the housing, and the powdery material may leak through agap between the agitating feeder and a die table of the turret.

SUMMARY OF THE INVENTION

It is an object of the present invention to improve flowability of apowdery material in an agitating feeder, improve uniformity in fillingthe powdery material in a die bore, and prevent the powdery materialfrom leaking through a gap between the agitating feeder and a die tableof a turret.

Specifically, an agitating feeder according to the present invention isprovided in a compression molding machine that includes at least one dieor a die table having a die bore, upper and lower punches retainedrespectively above and below the die so as to be vertically slidable,and a compression mechanism for compressing and molding a powderymaterial filled in the die bore by the upper and lower punches. Theagitating feeder includes an agitating rotor that rotates to agitate thepowdery material, a housing that accommodates the agitating rotor, and agas flow device that allows gas to flow in the housing.

In the above configuration, the gas flow device allows gas to flow inthe housing. Accordingly, the powdery material is agitated also by theflowing gas in the housing. Therefore, flowability of the powderymaterial is improved, which leads to improvement of uniformity infilling the powdery material in the die bore. Further, the powderymaterial is prevented from leaking through the gap between the agitatingfeeder and the die table of the turret. Moreover, gas flowing in thehousing smoothens rotation of the agitating rotor, so as to flow apowdery material that does not flow only by the rotation of theagitating rotor.

The “die table” in the present invention may be configured as a dieprovided with a die bore, or may be configured by providing a boreserving as a die bore directly in the table.

The gas flow device is not particularly limited as long as allowing gasto flow in the housing. The gas flow device is preferably configured tocirculate gas in the housing, or in the housing as well as in the regionof a powdery material supply mechanism, so as to flow the gas in thehousing.

It is not necessary to continuously flow the gas in the housing. Forexample, the gas may be caused to flow in the housing upon deteriorationof uniformity in filling the powdery material in the die bore, or at apredetermined interval.

As an example of a simple configuration for the agitating feeder, thegas flow device may include, in the housing, a first gas flowing rotorfor delivering gas upward, a gas passage allowing the gas delivered bythe first gas flowing rotor to flow therethrough, and a second gasflowing rotor for delivering downward the gas having flown through thegas passage. In such a configuration, the gas circulates in the housing,or in the housing as well as in the region of the supply mechanism.Therefore, flowability of the powdery material can be improved.

As an example of a specific configuration for the agitating feeder thatallows external gas to flow into the housing, the agitating feeder mayinclude a gas supply passage that supplies external gas caused to flowinto the housing, and an outlet bore portion that guides the gas fromthe gas supply passage into the housing.

As an example of a configuration for suppressing influence of variationin pressure in the housing on filling uniformity of the powdery materialin the die bore, there may be included a pressure sensor that senses thepressure in the housing, and a pressure control mechanism that receivesa pressure signal outputted from the pressure sensor and controls thepressure in the housing. When the powdery material is supplied into thehousing from a powdery material supplier, the pressure in the housing isvaried. However, the pressure in the housing can be kept within apredetermined range by controlling the pressure in the housing with useof the pressure control mechanism described above.

A compression molding machine including the agitating feeder describedabove achieves improvement of flowability of the powdery material, whichtherefore improves uniformity in filling the powdery material in the diebore. Moreover, the powdery material is prevented from leaking through agap between the agitating feeder and the die table of the turret.Furthermore, the gas flowing in the housing smoothens the rotation ofthe agitating rotors, so as to flow a powdery material that does notflow only by the rotation of the agitating rotor.

it is rioted that the “powdery material” in the present inventionconceptually indicates collective fine solids, inclusive of collectiveparticles such as granules and powdery bodies smaller than suchparticles.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of an entire configuration of a compressionmolding machine according to a first embodiment of the presentinvention;

FIG. 2 a partial enlarged plan view showing a state where an agitatingfeeder according to the embodiment is mounted;

FIG. 3 is a perspective view entirely showing the agitating feederaccording to the embodiment;

FIG. 4 is a plan view of the agitating feeder according to theembodiment;

FIG. 5 is a sectional view taken along line x-x of FIG. 4;

FIG. 6 is a perspective view of a gas flowing rotor included in theagitating feeder according to the embodiment;

FIG. 7 is a perspective view of a volume regulating plate included inthe agitating feeder according to the embodiment;

FIG. 8 is a plan view of a bottom plate included in the agitating feederaccording to the embodiment;

FIG. 9 is a sectional view of a main port ion of an agitating feederaccording to a second embodiment of the present invention;

FIG. 10 is a functional block diagram of a control unit according to adifferent embodiment of the present invention; and

FIG. 11 is a flowchart showing steps in a control operation that isperformed by the control unit according to the different embodiment ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Described below is a first embodiment of the present invention withreference to FIGS. 1 to 8.

As shown in FIGS. 1 and 2, a rotary compression molding machine 0includes an upright shaft 1, a frame 2, a turret 3, an upper punch 5,and a lower punch 6. The turret 3 serving as a die table is mounted tothe upright shaft 1 in the frame 2 so as to be horizontally rotatabletherein. The turret 3 is provided, at a predetermined pitch, with atleast one die that has a die bore 4. The upper punch 5 and the lowerpunch 6 are retained respectively above and below each die bore 4 so asto be vertically slidable. The rotary compression molding machine 0 alsoincludes a compression mechanism 8 for compressing and molding a powderymaterial filled in the die bore 4 by the upper punch 5 and the lowerpunch 6. The rotary compression molding machine 0 further includes asupply system 7 for filling the powdery material in the die bore 4. Thesupply system 7 is mounted so as to supply the powdery material fromabove the turret 3 toward a die table 31. There is provided, at a lowerend of the supply system 7, an agitating feeder F that fills the powderymaterial in the die bore 4. This agitating feeder F is disposed so as tobe pressed downward toward the die table 31.

The upright shaft 1, the frame 2, the turret 3, the die bore 4, and theupper punch 5 and the lower punch 6, as well as a mechanism for guidingthe upper and lower punches 5 and 6, a mechanism for ejecting a moldedproduct, a mechanism for rotating the upright shaft 1, and the like arebasically configured similarly to those well known in the art.Therefore, these components will not be detailed herein.

As shown in FIG. 1, the supply system 7 guides the powdery materialsupplied into a hopper 71 a to the agitating feeder F. The supply system7 includes a supply mechanism 71. The supply mechanism 71 supplies thepowdery material in the hopper 71 a to a supplying pipe 71 b. The supplymechanism 71 may be exemplified by a volumetric feeding device 71 e thatis provided with a detachable motor 71 f. Due to provision of thevolumetric feeding device 71 e, a volumetric feeding rotor is rotated bythe motor 71 f, and the powdery material is supplied from the hopper 71a to the supplying pipe 71 b. The hopper 71 a is in communication withthe supplying pipe 71 b by way of the volumetric feeding device 71 e,and is located at an upper end of the supplying pipe 71 b. The supplyingpipe 71 b guides the powdery material discharged from the hopper 71 a tothe agitating feeder F. The supplying pipe 71 b is provided, at anintermediate position, with a first degas bore 71 c that is incommunication with the outside of the supplying pipe 71 b. The firstdegas bore 71 c improves flowability of the powdery material in thesupplying pipe 71 b. Further, there is provided, above the supplyingpipe 71 b, a second degas bore 71 d that allows the inside and theoutside of the supplying pipe 71 b to be in communication with eachother. There is also provided, outside the supplying pipe 71 b, a passsensor 72. The pass sensor 72 is movable along the supplying pipe 71 b,and senses the powdery material that passes through the supplying pipe71 b.

The compression mechanism 8 is also basically configured similarly tothose well known in the art. As shown in FIG. 1, the compressionmechanism 8 includes paired pre-compression rolls configured by apre-compression upper roll 81 and a pre-compression lower roll 82, aswell as paired main compression rolls configured by a main compressionupper roll and a main compression lower roll (none of which beingshown). In a state where distal ends of the upper punch 5 and the lowerpunch 6 are inserted into the die bore 4, the powdery material filled inthe die bore 4 is compressed and molded while passing between thepre-compression upper roll 81 and the pre-compression lower roll 82, andthen between the main compression upper roll and the main compressionlower roll (none of which being shown). The upper rolls and the lowerrolls configuring the compression mechanism 8 are located around theupright shaft 1 and respectively above and below the turret 3.

The agitating feeder F fills the powdery material in a space formed bythe die bore 4 and the lower punch 6. The powdery material filledtherein is leveled by a leveling plate F5, and is then compressed andmolded by the upper punch 5 and the lower punch 6, as described earlier.

As shown in FIGS. 2 to 8, the agitating feeder F according to thepresent embodiment includes paired agitating rotors F1, and a housingF2. The paired agitating rotors F1 rotate in directions opposite to eachother to agitate the powdery material on the turret 3. The housing F2accommodates the agitating rotors F1.

As shown in FIGS. 4 and 5, the agitating rotors F1 each have anattachment flange F1 a and a plurality of, twelve for example, blades F1b. Each of the agitating rotors F1 is configured such that the blades F1b, which are identical in length, extend radially from the attachmentflange F1 a located at the center. Each of the blades F1 b has anagitating surface F1 c that is inclined upward from the rotationdirection. The right and left agitating rotors F1 are thus providedsymmetrically with each other. Each of the agitating rotors F1 is drivenby a gear F1 d that receives driving power transmitted from a motor (notshown) by way of a gear train (not shown). The agitating rotors F1 areaccommodated in a bottom space that is formed by a housing main body F3configuring the housing F2 and a bottom plate member F4 attached to abottom surface of the housing main body F3. The agitating rotors F1 arelocated substantially in the center in the longitudinal direction of theagitating feeder F, with distal ends thereof being overlapped with eachother so as not to hit each other during rotation thereof. The agitatingrotors F1 are mounted above and in no contact with an upper surface of abottom plate F4 a (to be described later) of the bottom plate member F4of the housing F2, in other words, such that the lower surfaces of theagitating rotors F1 are spaced apart from the upper surface of thebottom plate F4 a. Hereinafter, when the paired agitating rotors F1 arereferred to with no distinction from each other, each of them is simplyreferred to as the “agitating rotor F1”. Further, the agitating rotor F1located downstream in the rotation direction of the turret 3 is referredto as the “first agitating rotor F11”, while the agitating rotor F1located upstream in the rotation direction of the turret 3 is referredto as the “second agitating rotor F12”, respectively.

As shown in FIGS. 4 and 5, the housing F2 is assembled such that thebottom plate member F4 is detachably fixed to the bottom of the housingmain body F3 by means of bolts F21. Each of the bolts F21 penetrates thehousing main body F3 from above to reach the bottom plate member F4,while the distal end does not project from the lower surface of thebottom plate member F4. As shown in FIGS. 3 to 8, the housing main bodyF3 has an upper half portion provided with a first housing unit F3 athat accommodates the driving gear F1 d, and a lower half portionprovided with a second housing unit F3 b that accommodates the agitatingrotors F1. The housing main body F3 is also provided, on the uppersurface and at a position where the first housing unit F3 a is notlocated, with a powdery material supply port F3 c. This powdery materialsupply port F3 c allows the second housing unit F3 b to be incommunication with the powdery material supply system 7. The secondhousing unit F3 b has an inner space that is larger than the outerdiameters of the agitating rotors F1. There is also provided a volumeregulating plate F31 above the agitating rotors F1 in the second housingunit F3 b. The agitating rotors F1 and the powdery material agitated bythe agitating rotors F1 are accommodated in the space formed between thevolume regulating plate F31 and the bottom plate member F4.

As shown in FIG. 8, the bottom plate member F4 has a flat plate shapeand closes most of a lower opening of the second housing unit F3 b. Thebottom plate member F4 is provided with a groove F4 b in a circular arcshape, at a position included in the die bore 4 in a state where theagitating feeder F is mounted at a predetermined mounting position.Further, the groove F4 b is provided, at a terminal end thereof, withthe ing plate F5 for leveling the powdery material filled in the diebore.

As shown in FIGS. 4 and 5, in the present embodiment, there is alsoprovided a gas flow device F6 that allows gas to flow in the housing F2.

As shown in FIGS. 4 and 5, the gas flow device F6 includes a first gasflowing rotor F61, a gas passage F62, and a second gas flowing rotorF63. The first gas flowing rotor F61 is supported by a shaft F1 e thatpivotally supports the first agitating rotor F11, and delivers gas (airin the present embodiment) to above the first agitating rotor F11. Thegas passage F62 allows the air delivered by the first gas flowing rotorF61 to flow into the vicinity of the second agitating rotor F12. Thesecond gas flowing rotor F63 is supported by the shaft F1 e thatpivotally supports the second agitating rotor F12, and delivers the airhaving flown through the gas passage F62 downward into the vicinity ofthe second agitating rotor F12. The second gas flowing rotor F63 isprovided upstream in the rotation direction of the turret 3 with respectto the first gas flowing rotor F61.

As described above, the first gas flowing rotor F61 is supported by theshaft F1 e that pivotally supports the first agitating rotor F11. Asshown in FIG. 6, the first gas flowing rotor F61 has an agitatingsurface F61 a that is inclined upward from the rotation direction, and ashaft through bore F61 b that allows the shaft F1 e to be inserted therethrough. The gas flowing rotor F61 rotates synchronously with the firstagitating rotor F11, so that the air reaching the vicinity of the firstagitating rotor F11 is guided to above the first agitating rotor F11,more specifically, to above the volume regulating plate F31. While FIG.6 only shows the first gas flowing rotor F61, the second gas flowingrotor F63 may be configured identically with the first gas flowing rotorF61. In other words, the configuration of the second gas flowing rotorF63 may be obtained by vertically reversing the first gas flowing rotorF61. The second gas flowing rotor F63 is supported by the shaft F1 ethat pivotally supports the second agitating rotor F12. This second gasflowing rotor F63 rotates synchronously with the second agitating rotorF12. In other words, this second gas flowing rotor F63 rotates reverselyto the first gas flowing rotor F61 at an identical speed. Morespecifically, the second gas flowing rotor F63 has an agitating surfaceF63 a that is inclined downward from the rotation direction, and a shaftthrough bore F63 b that allows the shaft F1 e to be insertedtherethrough. This second gas flowing rotor F63 rotates reversely to thefirst gas flowing rotor F61 at an identical speed. Accordingly, airreaches the vicinity of the first agitating rotor F11 and then flowsreversely to the rotation direction of the turret 3 in the gas passageF62, which is subsequently guided downward into the vicinity of thesecond agitating rotor F12.

It is noted that the rotation speed of the first agitating rotor F11 maybe different from that of the second agitating rotor F12, and therotation direction of the former may be identical with that of thelatter. In the case where the first agitating rotor F11 and the secondagitating rotor F12 rotate in an identical direction, the first gasflowing rotor F61 is different in shape from the second gas flowingrotor F63, and these two rotors are respectively shaped so as to exertsimilar functions and effects.

As shown in FIGS. 4, 5 and 7, the gas passage F62 in the presentembodiment is configured by the volume regulating plate F31. Morespecifically, as shown in FIG. 7, the volume regulating plate F31 hasbores F31 a that allow the shaft F1 e pivotally supporting the pairedagitating rotors F1 to be inserted therethrough, and a concave grooveF31 b that is opened upward between these bores F31 a. The gas passageF62 is configured as a space formed between the bottom of the concavegroove F31 b and the housing main body F3.

In the present embodiment, there are further included an air importportion F81 for guiding air into the housing F2, and an air exhaustportion F82 for exhausting air from the housing F2.

As shown in FIG. 8, the air import portion F81 has an outlet boreportion F81 a and a gas supply passage F81 b. The outlet bore portionF81 a blows out air from below toward the bottom plate member F4 at aposition in the vicinity of the second agitating rotor F12. The gassupply passage F81 b supplies outside air toward the outlet bore portionF81 a.

The outlet bore portion F81 a is configured by a porous plate member.Air is allowed to flow upward from below the outlet bore portion F81 a.

The gas supply passage F81 b according to the present embodimentreceives air supplied from an air pump (not shown) through a gas inletport F81 c, and guides the supplied air to below the outlet bore portionF81 a.

The air exhaust portion F82 is configured by the supplying pipe 71 b andthe first degas bore 71 c provided in the supplying pipe 71 b. The airexhaust portion F82 may be located at any position. The air exhaustportion F82 may be provided in the upper surface of the housing mainbody F3, and is preferably provided above the bottom plate member F4.

In the present embodiment, positive pressure is applied to the vicinityof the second agitating rotor F12 due to the air flow caused by thesecond gas flowing rotor F63, while negative pressure is applied to thevicinity of the first agitating rotor F11 due to the air flow caused bythe first gas flowing rotor F61. Accordingly, there is generated in thegas passage F62 a gas flow from the vicinity of the second agitatingrotor F12 to the vicinity of the first agitating rotor F11, in adirection reverse to the rotation direction of the turret 3. Morespecifically, when the gas flow device F6 according to the presentembodiment is in operation, air flows from the vicinity of the firstagitating rotor F11 to the vicinity of the first agitating rotor F11 byway of the first gas flowing rotor F61, the gas passage F62, the secondgas flowing rotor F63, and the vicinity of the second agitating rotorF12, in this order. In other words, air circulates in the housing F2.

The present invention is not limited to the embodiment described above,but may be modified in various ways.

The present invention may include the following configuration accordingto a second embodiment, for example. In this embodiment, the volumeregulating plate F31 of the first embodiment is not provided, and thereis provided a gas flow device F6 configured as described below. In thefollowing description, portions corresponding to those of the firstembodiment are named identically and denoted by the same symbols. Thegas flow device F6 shown in FIG. 9 is configured as follows. There areprovided first and second air flow ports F91 and F92 that allow theinside and the outside of the housing F2 to be in communication witheach other. These first and second air flow ports F91 and F92 are incommunication with each other via a gas passage F64 that is provided asa tube or the like (not shown). This configuration allows air to flow inthe gas passage F64, from the first air flow port F91, which is locateddownstream in the rotation direction of the turret 3, to the second airflow port F92, which is located upstream in the rotation direction ofthe turret 3. Further, air is guided by the first gas flowing rotor F61of the first embodiment, from the inside of the housing F2 into the gaspassage F64 by way of the first air flow port F91. Then, the air isguided by the second gas flowing rotor F63 of the first embodiment, fromthe gas passage F64 into the housing F2 by way of the second air flowport F92. As a result, circulation of air is realized. Alternatively,there may be provided, in the gas passage F64, a gas flow promotingdevice such as a gas flow promoting rotor, which is driven by a motor,so that the air flow in the housing F2 is promoted. Flowability of thepowdery material can be improved also by circulating air reversely tothe above example.

Still alternatively, the first or second air flow port F91 or F92 maynot be provided, and air exhausted from the air exhaust portion F82 ofthe above embodiment may be made to return into the housing F2, so as tobe circulated. This configuration prevents the powdery material fromleaking through the air exhaust portion F82.

Still alternatively to the use of the circulation of gas in theagitating feeder F as described above, there may be adopted a gas flowdevice that includes a gas importing device for importing gas such asair into the housing of the agitating feeder, and a gas exhaustingdevice for exhausting gas such as air from the housing of the agitatingfeeder. This gas flow device utilizes the flow of gas from a gas outletport of the gas importing device toward a gas exhaust port of the gasexhausting device. As one example, the volume regulating plate F31 ofthe first embodiment is not provided, and the air import portion F81 ofthe above embodiment is used as the gas importing device, and the airexhaust portion F82 of the above embodiment is used as the gasexhausting device.

Further, an exemplary configuration for stabilizing the powdery materialin the agitating feeder F may include a pressure censor F7 and apressure control system F8. The pressure sensor F7 senses the pressurein the housing F2. The pressure control system F8 receives a pressuresignal outputted from the pressure sensor F7 to control the pressure inthe housing F2.

As shown in FIG. 10, the pressure control system F8 includes the airimport portion F81, a flow control valve F83, the air exhaust portionF82, a suction unit F84, a control unit F85, and a display unit F86. Theflow control valve F83 controls the flow rate of air imported into thehousing F2 through the air import portion F81. The suction unit F84discharges air from the housing F2 through the air exhaust portion F82.The control unit F85 includes an import rate controller and a suctionpower controller. The import rate controller controls the rate of airimported into the housing F2 from the air import portion F81. Thesuction power controller controls suction power for sucking atmosphericair in the housing F2 through the first degas bore 71 c. When thecontrol unit F85 outputs an operation stop signal indicative ofabnormality of the pressure in the housing F2, the display unit F86receives the operation stop signal and visually indicates that thepressure in the housing F2 is abnormal. The pressure control system F8controls the pressure in the housing F2 by controlling the rate ofimported air and suction power with use of the import rate controllerand the suction power controller, respectively, on the basis of thepressure in the housing F2 measured by the pressure sensor F7. The gasused in this case is not limited to air, but may be nitrogen, oxygen,inert gas, or any other kind of gas.

Although not shown, the control unit F85 is mainly configured by acomputer system that includes a central processing unit, a storage unit,an input interface, and an output interface. The central processing unitexecutes a pressure control program stored in the storage unit andfunctions as a suction power measurement device and as the suction powercontroller, so as to control the pressure in the housing F2. Morespecifically, the central processing unit receives a signal from thepressure sensor F7 by way of the input interface, and transmits acontrol signal to each of the flow control valve F83 and the suctionunit F84 by way of the output interface.

The control process performed by the control unit F85, which executesthe pressure control program, is detailed below step by step withreference to the flowchart shown in FIG. 11. It is noted that thepressure control program is continuously executed while the compressionmolding machine 0 is in operation.

Initially in step S1, the pressure in the housing F2 is measured. Morespecifically, the central processing unit receives a signal indicativeof the pressure in the housing F2 from the pressure sensor F7. Then instep S2, the control unit F85 determines whether or not the pressure inthe housing F2 has a value within a first predetermined range. If it isdetermined in step S2 that the pressure in the housing F2 has the valuewithin the first predetermined range, the pressure in the housing F2 isnormal, so that the process returns to step S1.

To the contrary, if it is determined in step S2 that the pressure in thehousing F2 is not within the first predetermined range, it is determinedin step S3 whether or not the pressure in the housing F2 has the valuewithin a second predetermined range.

In this case, the second predetermined range has an upper limit that ishigher than the upper limit of the first predetermined range, and alower limit that is lower than the lower limit of the firstpredetermined range. The second predetermined range includes the firstpredetermined range and a range that can be modified into the firstpredetermined range. This range can be defined by arbitrarily setvalues.

If it is determined in step S3 that the pressure in the housing 52 isnot within the first predetermined range but within the secondpredetermined range, then in step S4, the import rate controller and thesuction power controller control the flow control valve 583 and thesuction unit 584, respectively, and regulate the flow rate of airimported into the housing 52 and suction power of the suction unit, sothat the pressure in the housing F2 has a value within the firstpredetermined range.

To the contrary, if it is determined in step S3 that the pressure in thehousing 52 is not within the second predetermined range, then in stepS5, the control unit F85 outputs an operation stop signal indicative ofabnormality of the pressure in the housing F2.

When the powdery material is supplied from the powdery material supplier7 into the housing F2, the pressure in the housing F2 is varied. In theabove configuration, the agitating feeder F includes the pressure sensorF7 for sensing the pressure in the housing F2, and the pressure controlsystem F8 for receiving a pressure signal outputted from the pressuresensor F7 and controlling the pressure in the housing F2. Accordingly,the pressure in the housing F2 is controlled by the pressure controlsystem F8 so as to keep the pressure in the housing F2 within apredetermined range. Suppressed therefore is influence of variation ofthe pressure in the housing F2 onto filling uniformity of the powderymaterial in the die bore.

In the agitating feeder configured as described above, the first degasbore 71 c in the air exhaust portion F82 functioning as the gasexhausting device may be connected to the gas inlet port 581 c in theair import portion F81 functioning as the gas importing device. In thisconfiguration, air exhausted from the housing F2 through the powderymaterial supply port F3 c can circulate from the inside of the supplyingpipe 71 b into the gas inlet port F81 c through the first degas bore 71c.

Still alternatively, in each of the above embodiments, the number of theagitating rotors may be one, or may be three or more. In addition, eachof the agitating rotors may be formed in any shape.

Moreover, the gas allowed to flow by means of the gas flow device is notlimited to air, but may be a different kind of gas such as nitrogen.Such gas may be selected appropriately according to the type of thepowdery material as well as functions and effects. In place of the passsensor 72 of the first embodiment described above, there may be provideda flow rate sensor that senses the flow rate of the powdery material.

In place of the gas flow device configured to circulate gas as in theabove embodiments, there may be adopted a gas flow device that utilizesonly the flow of gas from a gas importing port for guiding air into thehousing toward a gas exhaust port for exhausting gas from the housing.Examples of such a gas flow device include a blower, a cooling fan, andan air heater.

The present invention is applicable not only to the rotary compressionmolding machine according to the embodiments described above, which hasa die provided in a turret, but also to a nonrotary compression moldingmachine.

Other than the above, various modifications may be made to the presentinvention as long as not departing from the purpose of the presentinvention.

1. An agitating feeder provided in a compression molding machine thatincludes at least one die having a die bore, an upper punch and a lowerpunch retained respectively above and below the die so as to bevertically slidable, and a compression mechanism for compressing andmolding a powdery material filled in the die bore by the upper punch andthe lower punch, the agitating feeder comprising: an agitating rotor forrotating to agitate the powdery material; a housing accommodating theagitating rotor; and a gas flow device for flowing gas in the housing.2. The agitating feeder according to claim 1, wherein the gas flowdevice includes, in the housing, a first gas flowing rotor fordelivering gas upward, a gas passage allowing the gas delivered by thefirst gas flowing rotor to flow therethrough, and a second gas flowingrotor for delivering downward the gas having flown through the gaspassage.
 3. The agitating feeder according to claim 1, furthercomprising: a gas supply passage for supplying from outside the gasflowing in the housing; and an outlet bore portion for guiding the gasfrom the gas supply passage into the housing.
 4. The agitating feederaccording to claim 1, further comprising: a pressure sensor for sensinga pressure in the housing; and a pressure control mechanism forreceiving a pressure signal outputted from the pressure sensor andcontrolling the pressure in the housing.
 5. A compression moldingmachine comprising the agitating feeder of claim
 1. 6. The agitatingfeeder according to claim 2, further comprising: a pressure sensor forsensing a pressure in the housing; and a pressure control mechanism forreceiving a pressure signal outputted from the pressure sensor andcontrolling the pressure in the housing.
 7. The agitating feederaccording to claim 3, further comprising: a pressure sensor for sensinga pressure in the housing; and a pressure control mechanism forreceiving a pressure signal outputted from the pressure sensor andcontrolling the pressure in the housing.
 8. The agitating feederaccording to claim 6, further comprising: a gas supply passage forsupplying from outside the gas flowing in the housing; and an outletbore portion for guiding the gas from the gas supply passage into thehousing.
 9. A compression molding machine comprising the agitatingfeeder of claim
 2. 10. A compression molding machine comprising theagitating feeder of claim
 3. 11. A compression molding machinecomprising the agitating feeder of claim
 4. 12. A compression moldingmachine comprising the agitating feeder of claim
 6. 13. A compressionmolding machine comprising the agitating feeder of claim
 7. 14. Acompression molding machine comprising the agitating feeder of claim 8.